The present invention relates to an electrical control circuit for controlling the operation of a pilotless gas system. The invention finds particular utility in use with a regulated sealed combustion heating system, but can also be used in a wide variety of gas systems and appliances which require safety controls.
It is important for reasons of safety that gas appliances be equipped with a flame detection and control circuit which will assure shut off of gas when no flame is present. The control must also allow for a period of ignition when the gas is on even though there is no flame. When the gas has not been ignited, the system must operate to quickly close the gas valve.
There are a number of types of gas appliances, including heating and air conditioning systems, stoves, dryers, etc., for which such a flame detection and proof device is required. For many years, gas appliances have operated with a pilot light system which ignites the main gas jet when the appliance is turned on. However, in recent years it has been recognized that such systems are not fuel or energy efficient. Consequently, other systems have been introduced to replace the pilot light type of system.